creatuREport: Fireflies

It’s Energy Week, so of course I had to pick an organism that can relate. I’ve chosen fireflies (or lightning bugs) because they don’t need to burn coal, collect the Sun’s energy, or support nuclear fission in order to turn on the lights. They produce the glow themselves. Brilliant.

The 2,000 or so species of fireflies prefer warm to temperate areas and are usually out and about during the summer, around dusk or later. They are more likely to be found around wet or humid areas. They are omnivorous but their diet depends on what developmental stage they are in. Larvae eat worms, slugs, or similar ground prey. Adults tend to feed on plant sources such as nectar, and some do not eat at all – their adult lives are only long enough to reproduce. Eggs are deposited in the ground so that food will be close by when the critters hatch. Larvae hibernate during the winter.

Fireflies are nocturnal beetles and are close relatives of glowworms (some may use the term glowworm to refer to the larval stage of fireflies). Their bodies are relatively flat and shaped like an elongated oval, and their wings are typically dark or black with a lighter-colored outline which makes them look a bit like sunflower seeds. On their underside they have little segments at their tail end that hold their bioluminescent magic.

These segments are actually specialized organs with cells that use a substance called luciferin and the enzyme luciferase to produce a light which scientists refer to as cold light. It is said that fireflies produce the most efficient light possible. It is called cold because there is no heat given off in the process. The light can be green, yellow, or a dull reddish orange. Even larvae have bioluminescent abilities. In adults, the flashes of light are unique to each species and are used to attract potential mates. As larvae these glowing abilities are likely a warning sign for predators.

Some female fireflies imitate the flashing patterns of other species in order to attract males and then eat them. They are sometimes referred to as femme fatale fireflies because of this. Some species do not glow at all and are usually active during the day.

Risks to Fireflies

Luciferase, the enzyme that makes bioluminescence possible, has been found to be useful in a range of applications including research, food safety, and forensics. Originally fireflies were the only source of this enzyme. Although we now have a synthetic version, some companies still collect it from fireflies which may harm their populations.

Habitat loss is another consideration as more and more forests and open fields become department stores and parking lots. Light pollution can also cause problems in their mating rituals.

The biggest risk of all is a kid with a mason jar. Joking of course, but if you’re going to go out and catch fireflies, be sure to poke holes in the jar’s lid first and add a wet paper towel or small cloth in the bottom, and maybe a few twigs for them to land on. Release them the next day, or sooner if possible. They are fascinating creatures but we want to do as little harm as possible.

Here is a fun web page that has a firefly background and some sliders to allow you to change some factors for their flashing.

Glow bright. Be radiant. Shine on.

Ok I’ll stop.

*This post is part of HFTH’s Energy Week 2017! Stay tuned for more energy-related topics!*